This invention relates to devices for recording and reproducing information by use of a small-size optical magnetic disk such as a mini disk or the like.
Disk recording and reproducing devices have been known which record and reproduce information using a mini disk as a recording medium. The mini disk commonly known as MD, which is based on a novel sound compression/expansion technique as well as a known sampling technique as employed in a conventional Compact Disc (CD), provides as high sound quality as does the Compact Disc, requiring only about one-fifth of information amount normally required by the CD.
Since the recordable and reproducible mini disk is an optical magnetic disk, a device for recording and reproducing information onto and from such a mini disk ("MD player") is provided with a recording/reproducing optical head and a magnetic head that is used in combination with the optical head in recording desired information on the disk. For normal operation of the device, a user selects either a reproduction mode to reproduce data from the disk or a recording mode to write data onto the disk.
In the reproduction mode, data recorded in compressed form on the disk are intermittently read out from the disk to be intermittently written into a buffer memory at a rate of, say, 1.4 Mb/s, during which time the thus-written data are successively read out from the buffer memory at a rate of, say, 0.3 Mb/s and subjected to a data expansion process. The resultant expanded data are then output as reproduced data signals.
In the recording mode, data signals to be recorded are compressed and successively written into the buffer memory at a rate of, say, 0.3 Mb/s, during which time the thus-written data are intermittently read out from the buffer memory at a rate of, say, 1.4 Mb/s to be recorded onto the disk in an intermittent manner.
Even when there has been caused deviation in the disk tracking servo due to an external disturbance, the above-mentioned buffer memory functions to successively allow the reproduced data signals to be output therefrom and allow the data signal to be recorded to be input thereto until all the data stored in the memory have been completely read out (hereinafter, this function-will be called a "shockproof function").
Recorded music data, for example, are sometimes processed for desired editing while being reproduced. In such a case, an editing mode has to be set which provides combined functions of the recording and reproduction modes. Among various expected editing functions may be an overdubbing function for re-recording in real time already-recorded data after mixing new music data to part of the data while the latter is reproduced, a so-called ping-pong recording function for re-recording in real time a plurality of already-recorded data after reproducing and mixing together the plurality of data, a punch-in/punch-out function for changing part of already-stored data into new music data, etc.
However, in realizing the above-mentioned editing mode with the conventional disk recording and reproducing devices, the reproduction and recording systems of the devices would require separate buffer memories and memory controllers for the simultaneous reproduction and recording operations, thus resulting in complicated construction.